Bicycle Cuff

ABSTRACT

A lightweight and portable bicycle cuff is disclosed to protect the lower leg, pants, and shoe of a bicycle rider from the effects of dirt, grease, and an exposed chain and front gear(s) while having minimal impact on pedaling by the bicycle rider. In certain embodiments the bicycle cuff provides increased visibility to traffic while riding. In some embodiments the cuff includes a flexible, water resistant woven material which conforms generally to the rider&#39;s ankle and foot by means of tailored shaping of the woven material, a strip of reflective material along the rear ankle area, and a loop and hook style closure on one side. In these embodiments the cuff covers from just above the ankle to approximately one third of the way down the front of the rider&#39;s shoe and just over the edge of the back of the rider&#39;s shoe.

PRIORITY TO EARLIER FILED PROVISIONAL PATENT APPLICATION

This application claims the benefit of the filing date of earlier filed co-pending U.S. Provisional Patent Application having Ser. No. 61/725,261 entitled “BICYCLE CUFF,” filed Nov. 12, 2012 and that shares co-inventorship with the present application. The entire teachings and contents of this Provisional Patent Application are hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to lightweight and portable bicycle riding gear, clothing, and accessories, in particular to bicycle cuffs protecting the lower leg, pants, and shoes of bicycle riders from the effects of dirt, grease, and an exposed chain and front gear(s).

BACKGROUND

People riding bicycles are often exposed to damage to their clothing and their health from the condition of their bicycle chain and front gear(s), and their proximity to loose articles of clothing near the feet and ankles. While riding a bicycle, a rider's right leg circulates repeatedly in close proximity to the bicycle chain and front gear(s). This proximity is often less than the width of the rider's pant cuff, or the length of the rider's shoelaces. As a result, the material of the rider's pants frequently comes into contact with the bicycle chain and front gear(s), causing grease and dirt to damage the lower portion of the right pant leg. Damage also occurs when the right shoelace sometimes becomes caught between the chain and front gear(s), resulting in potentially dangerous accidents when the bicycle suddenly stops due to the caught shoelace. A rider's shoes may also accumulate dirt and grease from proximity to the bicycle chain, causing damage to potentially expensive footwear.

Some riders combat these effects by riding only in clothing specially designed for bicycle riding, or by limiting themselves to riding only in clothing that is either not valuable to them or that is cut very slim at the ankle, such as leggings, or shoes without laces, to try to avoid coming into contact with their chain and front gear(s). However this is not a workable solution for the many riders who use bicycles as their primary mode of transportation, especially to and from work. Many of these riders must bring appropriate clothing with them to work, biking in completely separate outfits, and then somehow change upon arrival, necessitating carrying an entire outfit change with them on the bike. Or they must choose only to bike when they do not have to wear clothing that they either value or does not conform to the constrictions (slim ankles, no laces) that would be required for a safer, cleaner ride.

Conventional options for preventing damage to the rider and his/her clothing have so far focused almost exclusively on minimizing the distance between the right pant leg at the ankle and the bicycle chain, providing minimal coverage of the actual pant or ankle, and no coverage of the foot or shoelaces. They have come largely in the form of strips, sometimes reflective, which band around the ankle but leave the hem of the pants to spread out and still potentially come into contact with dirt, grease, chains, and gears. These strip-style ankle wraps come in a variety of materials and thicknesses, none of which provide any protection for the full bottom of the pant leg, or the shoe and shoelaces of the rider. There have also been metal clips to again attempt to minimize the distance between the rider's pant leg and bicycle chain, but these too suffer from the same short comings as just noted for the strip-style ankle wraps, as well as having the additional failure of often popping right off of the rider's pant if not secured appropriately, or if strained by motion of the pant on the leg while riding. The aforementioned options also do not provide any form of fashionable camouflage for the rider, as they often stand out in stark contrast to what the rider is wearing. When riding in clothing that is not specifically designed for cycling, this is often a negative as the rider wishes to travel as seamlessly on a bicycle as he or she might by foot, subway, bus, or car. Any accessory that is seen to make the rider less stylish or more encumbered is often skipped in favor of alternatives that inevitably result in damage to the rider's skin and clothing, such as rolling up the right pant leg (which often results in grease on the leg itself and interior of the right pant leg) or stuffing the right pant hem inside the rider's sock (which is often unsightly and usually results in grease and dirt on the rider's sock). Other leg protection devices (e.g., gaiters and leggings) interfere with the pedaling motion by restricting ankle motion and interfering with the bicycle rider's shoe. Therefore there exists a need for adequately protecting the legs, pants, shoes and laces of bicycle riders from damage that can commonly occur due to contact with the bicycle chain and front gears while riding without interfering with the rider's pedaling motion.

SUMMARY OF THE INVENTION

In one embodiment, a cuff for a bicycle rider includes an instep flap made from a flexible fabric generally trapezoidal shaped, and having a instep flap top edge, a instep flap bottom edge, a instep flap front edge and an instep flap back edge, a front flap made from a flexible fabric generally quadrilateral shaped having a front flap top edge, a front flap bottom edge, a front flap closure edge and an front flap attachment edge, the front flap attachment edge joined with the instep flap front edge and a back flap made from a flexible fabric generally quadrilateral shaped having a back flap top edge, a back flap bottom edge, a back flap closure edge and a back flap attachment edge, the back flap attachment edge joined with the instep flap back edge. In this embodiment, the instep flap, the back flap and the front flap are tailored to curve around the rider's ankle and shoe, so as to cover approximately from just above the top of the rider's ankle to just below the top of a rider's shoe and to follow the general contour of the rider's ankle. Such a device provides protection from dirt and grease found on bicycle chains and front gears for the legs, pants, shoes, and shoelaces of bicycle riders and is pleasing to look at and merges well with their chosen apparel. The disclosed bicycle cuff also provides a safer ride for bicycle riders by keeping loose material from pant legs and shoelaces away from bicycle chains and front gears, which can potentially cause accidents and provides bicycle riders with leg, pant, shoe and shoelace protection that is durable under riding conditions.

Another embodiment of the protective cuff apparatus includes a flexible material having an outside surface and an inside surface and a first end and a second end and a top edge and a bottom edge, at least one coupler to secure the first end to the second end to shape the cuff apparatus into a cuff. The top edge has a length that is shorter than the bottom edge so that when the coupler secures the first end to the second end, the protective cuff formed by the flexible material flares outwards from the top edge to the bottom edge and at least one coupler is operable to secure the protective cuff apparatus around an ankle and upper foot region of a person operating a bicycle, the protective cuff apparatus protecting at least a portion of a wearable item worn by the person operating the bicycle. Such an apparatus provides leg, pant, shoe and shoelace protection that is easy for riders to put on and remove and can easily be rolled, folded, and carried by the cyclist when not riding. The disclosed embodiment also can be easily adjusted to fit a wide range of ankle and shoe sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of embodiments of the invention, as illustrated in the accompanying drawings and figures in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating the embodiments, principles and concepts of the invention. These and other features of the invention will be understood from the description and claims herein, taken together with the drawings of illustrative embodiments, wherein:

FIG. 1 is a side view of a cuff worn over a pant leg and shoe according to an embodiment disclosed herein.

FIG. 2A is a view of the assembled cuff of FIG. 1 from the side worn on the interior of the right leg.

FIG. 2B is a top view of the assembled cuff of FIG. 1.

FIG. 2C is a view of the assembled cuff of FIG. 1 from the side worn on the exterior of the right leg.

FIG. 2D is a rear view of the assembled cuff of FIG. 1.

FIG. 3A is an inside view of the cuff of FIG. 1, unassembled, facing the interior of the cuff, which faces the body when worn.

FIG. 3B is an outside view of the cuff of FIG. 1, unassembled, facing the exterior of the cuff, which faces out when worn.

DETAILED DESCRIPTION

One embodiment of the cuff disclosed herein includes a woven nylon material coated on one side with urethane for water-resistance (referred to as water resistant urethane-coated nylon), loop and hook style closure on one side, reflective material at the center back vertical seam, and a brand logo label at the top left hand corner of the opening flap, on the outside of the cuff. The shape of the cuff approximately follows the curve of the rider's foot from ankle to the edge of the instep at the center front, and from ankle to the top of the heel at the center back. The loop and hook style fastener lies approximately halfway between the center front and center back of the foot, on the outside of the right leg. The cuff material runs from just above the ankle to just below the start of the heel of the foot (at the back center seam) and just beyond the start of the foot's instep (at the front center seam). The cuff is shaped to allow it to fall at these points on the ankle and the foot for most riders without requiring multiple sizes. The loop and hook-style closure is to be wide enough to allow for a tighter or looser fit around the ankle for riders of varying sizes, without compromising the alignment of the center front and back seams on the foot. The cuff material can optionally be any material that is water-resistant and flexible enough to be sewn into the necessary tailored shape, worn under riding conditions, and rolled, folded, and carried by the rider. The cuff is designed to leave the bottom of the rider's shoe exposed and thus mimic the look of the bottom of a pant leg while still covering and protecting the bottom of the rider's actual pants and tops of their shoes and shoelaces.

Now referring to FIG. 1, an embodiment of the cuff 100 is shown assembled over a pant leg 104 and shoe 105. The cuff 100 (also referred to as protective cuff apparatus 100) is secured around an ankle and upper foot region of a person operating a bicycle protecting at least a portion of a wearable item worn by the person operating the bicycle. Here the cuff 100 protects the pant leg 104, shoe 105 and shoe laces (not shown).

Now referring to FIG. 2A, the exemplary cuff 100 of FIG. 1 includes an instep flap 109 which is made from a flexible fabric generally trapezoidal shaped, and has an instep flap top edge 120, an instep flap bottom edge 122, an instep flap front edge 123 and an instep flap back edge 124. The cuff 100 optionally includes a reflective strip 102 (a portion is shown for clarity).

Now referring to FIG. 2C, the cuff 100 of FIG. 1 further includes a front flap 107 made from a flexible fabric generally quadrilateral shaped having a front flap top edge 112, a front flap bottom edge 113, a front flap closure edge 140 and an front flap attachment edge 115, the front flap attachment edge 115 joined with the instep flap front edge 123. The cuff 100 of FIG. 1 further includes a back flap 108 made from a flexible fabric generally quadrilateral shaped having a back flap top edge 132, a back flap bottom edge 133, a back flap closure edge 142 and a back flap attachment edge 114, the back flap attachment edge 114 joined with the instep flap back edge 124. The instep flap 109, the back flap 108 and the front flap 107 are tailored to curve around the rider's ankle and shoe, so as to cover approximately from just above the top of the rider's ankle to just below the top of a rider's shoe and to follow the general contour the rider's ankle.

The instep flap front edge 123 and corresponding front flap attachment edge 115 and the instep flap back edge 124 and corresponding back flap attachment edge 114 are contoured to provide coverage and protection simultaneously to the bottom of the rider's pant leg 104 and leg and to of the top portion of the rider's foot, shoe 105, and shoelaces if applicable.

Referring to FIG. 2D the reflective strip 102 is shown attached along the back seam 152 formed where the back flap attachment edge 114 and the instep flap back edge 124 are joined. The reflective strip 102 is aligned with the back of the rider's ankle and heel of the rider's shoe. Alternatively a reflective device or multiple reflective devices could be placed anywhere on the cuff 100 that allows for safe passage of the rider's foot near the bicycle chain and front gear without interfering with riding.

Now referring to FIGS. 2B and 2C, a brand label 103 (also referred to as logo 103) can be optionally placed on the cuff 100. In one embodiment, the brand label 103 is approximately 1½ inches wide by 1 inch high and on the cuff 100 is located within ¼ inch of the both the front flap top edge 112 and the front flap closure edge 140 of the front flap 107. The brand label or logo 103 may be placed anywhere on the inside or outside of the cuff 100, such as on the instep flap 109, the front flap 107, or the back flap 108, including potentially covering a portion of the reflective strip 102. The size of the logo 103 may also be enlarged to fit in part or in total on a greater portion of any part of the cuff 100. Additional logos 103 may be added so that there is more than one logo, brands, or decorative designs represented on any portion of the cuff 100. Logos 103 may be attached by means of sewing, gluing, screen printing, digital printing, drawing, embroidering, heat adherence, and the like.

Referring again to FIG. 2B, the assembled cuff 100 of FIG. 1. FIG. 2C shows a side view of the assembled cuff 100 of FIG. 1 from the exterior of the leg, the same perspective as shown in FIG. 1. FIG. 2D shows the assembled cuff 100 of FIG. 1 from the back of the cuff, which aligns with the back ankle and heel of the rider when worn. FIG. 3A shows a view of the cuff 100 unassembled, facing the interior of the cuff, which faces the body when worn. FIG. 3B shows a view of the cuff 100 unassembled, facing the exterior of the cuff, which faces out when worn.

In one embodiment, the cuff 100 is comprised of a flexible, woven, water resistant material 101 cut from three highly shaped pieces front flap 107, back flap 108, and instep flap 109 and sewn to create a single contoured cuff 100. Alternatively the three pieces can be connected using gluing or like methods. Alternatively, the cuff 100 can be any flexible material having an outside surface and an inside surface and a first end and a second end and a top edge and a bottom edge. If the cuff is made from multiple pieces, once they are connected (e.g. sewn together), the pieces form a single piece of flexible material. Suitable flexible materials include woven and non-woven flexible materials such as nylon, vinyl, cotton, synthetic wovens, woven cloth, non-woven cloth and the like, with or without water resistant properties or coatings.

Alternatively the cuff can be cut from a single piece of flexible material and still contoured as shown between sections front flap 107, back flap 108 and instep flap 109 using contoured tucks or folds (sometimes called darts) to create the final resulting shape. Useful contouring techniques include but are not limited to sewing, gluing, snapping, tying and the like. In one embodiment, the approximate dimensions of the assembled cuff 100 are 4 inches high at the edge of the front flap 107 with an top opening 150 formed by the top edges of the front flap 107, the back flap 108 and the instep flap 109 having a circumference of between 9 inches and 12 inches and a bottom opening (not shown) formed by the bottom edges of the front flap 107, the back flap 108 and the instep flap 109 having a circumference of between 14 inches and 17 inches. It is noted that the top opening 150 is smaller (i.e., has a smaller circumference) than the bottom opening. Thickness of the flexible material can vary, and in one embodiment the material is approximately 1/32 inch. It is understood that the cuff 100 can be formed according to either a broad size range (for example XS-XL, etc.) or sized to specific shoe and ankle sizes by re-sizing (sometimes called grading) the patterns for the three highly shaped pieces front flap 107, back flap 108, and instep flap 109 to adjust their overall dimensions according to the parameters of each size. This can be done without changing the overall shape and function of the cuff 100. The cuff 100 can come in any color or finish desired by the rider for which a suitable material can be found. While in one embodiment, the cuff 100 has a “right leg” configuration, in other embodiments the cuff 100 can be formed to fit the left leg and left foot as well.

Referring to FIGS. 3A and 3B, details of the assembly of the cuff 100 are shown. The front flap 107 includes a loop fastener 110 aligned with the front flap closure edge 140 and the back flap 108 includes a hook fastener 111 aligned with the back flap closure edge 142. Fasteners or couplers can each be a single piece of loop and hook-like material, or can be made from a total area of smaller loop and hook-like pieces. It is understood that the loop fastener 110 and the hook fastener 111 can be exchanged. In one embodiment, the cuff 100 includes single pieces of loop and hook-like hook and loop fasteners 111 and 110 approximately 2 inches wide by 3.75 inches long. The area of the back flap 108 and front flap 107 which is covered by the hook and loop fasteners 111 and 110 can be smaller or larger than the cuff 100 shown, with an approximate range of width being ¼ inch to 3½ inches wide and up to the full length of the cuff 100 from top opening 150 to bottom opening (FIG. 2B). Alternatives to the cuff 100 include extending hook and loop fasteners 111 and 110 around the full top or bottom circumference of the cuff 100, allowing for a total width of up to 18 inches. The hook and loop fasteners 111 and 110 can be attached to the front flap 107 and back flap 108, by means of sewing, gluing, and the like. It is understood that other fasteners, including but not limited to, snaps, buttons and buckles can be substituted for the hook and loop fasteners 111 and 110. In one embodiment, the hook and loop fasteners 111 and 110 are shown located within ¼ inch of the edges of the front flap 107 and back flap 108. Approximate location of the hook and loop fasteners, or of any alternative fasteners, may vary according to the size of the cuff 100, should the cuff be resized (sometimes called graded) to fit a different range of legs and shoes. Thus the cuff 100 as shown includes at least one coupler (i.e. fastener) to secure the first end of the cuff to the second end of the cuff to shape the cuff apparatus into a cuff as shown by way of example. The top edge has a length that is shorter than the bottom edge so that when the hook and loop fasteners 111 and 110 secure the first end of the flexible material to the second end of the flexible material, the cuff formed by the flexible material flares outwards from the top edge to the bottom edge to conform to the shape of the lower leg and ankle region of a person's leg and foot region. In one embodiment, the flared design covers the front and back of the rider's shoe and thereby protects the shoe without impeding the pedaling motion of the rider. The fastener or coupler is operable to secure the protective cuff apparatus around an ankle and upper foot region of a person operating a bicycle. The protective cuff apparatus protects at least a portion of a wearable item worn by the person operating the bicycle.

The front flap 107 and back flap 108 could also be replaced with a single piece of material similar to the instep 109, so that the cuff comprises of two instep 109 pieces with an enlarged top opening 150, FIG. 2B). The hook and loop fasteners could then be eliminated and replaced with elastic or other flexible material at the top opening 150, FIG. 2B) to allow the rider to slip the cuff 100 on over their shoe.

Again referring to FIGS. 1, 3A, and 3B, in use the hook and loop fasteners 111 and 110 are initially disconnected. The rider aligns the interior of the back seam 152 with the back of his or her ankle and foot over his or her pant leg 104 and shoes 105, and wraps the back flap 108 around to the outside of his of her ankle and foot. He or she then aligns the front flap attachment edge 115 with the front center of his or her foot and continues to wrap the front flap 107 around so that the loop fastener 110 on the inside of the front flap 107 meets with the hook fastener 111 on the outside of the back flap 108. The rider adjusts the overlap of the hook and loop fasteners 111 and 110 as needed to accommodate the size of his or her ankle and foot, including his or her pant leg 104 and shoes 105. Before mating the hook and loop fasteners 111 and 110 the rider may also lift his or her shoelaces and tuck them up under the bottom opening of the cuff 100. Then by mating the hook and loop fasteners 111 and 110 his or her shoelaces may be secured between the top opening 150 and bottom opening of the cuff 100, keeping them away from the bicycle chain and front gear.

It is understood that a protective cuff can be assembled from a single section (or multiple sections) of flexible material having an outside surface and an inside surface and a first end and a second end and a top edge and a bottom edge; at least one coupler to secure the first end to the second end to shape the cuff apparatus into a cuff; the top edge having a length that is shorter than the bottom edge so that when the coupler secures the first end to the second end, the protective cuff formed by the flexible material flares outwards from the top edge to the bottom edge; the at least one coupler operable to secure the protective cuff apparatus around an ankle and upper foot region of a person operating a bicycle, the protective cuff apparatus protecting at least a portion of a wearable item worn by the person operating the bicycle. Such a protective cuff has a similar shape and functionality as the cuff described above in conjunction with FIGS. 1-3B

While some embodiments are described using a flexible, woven, water resistant material for the invention, other types of materials are also applicable. For example, woven and non-woven flexible materials such as nylon, vinyl, cotton, synthetic wovens, and the like, with or without water resistant properties or coatings. The materials used in the cuff may be flexible and durable so as to permit folding, crushing, or rolling of the material for ease of carrying in a backpack, pocket, purse, saddle bag, briefcase, and the like.

While the embodiments are not described as being any particular color, materials can include any range of colors that suitable materials are manufactured in, including black, khaki, bright colors, metallic colors, printed patterns, textured surfaces, glow in the dark, reflective, clear, and the like. Additionally the cuff could be constructed from multiple pieces of different colors, not limiting each cuff to one single color or pattern. Further a portion of the cuff can include space for brand logos 103, FIG. 1) and the like. The type of pant legs around which the cuff can be worn includes but is not limited to straight pant legs, bellbottoms, flares, skinnies or tapered styles, trousers, leggings, and the like. The type of shoes over which the cuff can be worn includes but is not limited to sneakers, boots, loafers, cycling shoes, sandals, pumps, flats, and the like. The embodiment has been described using hook and loop style fasteners such as loop and hook, but other types of fasteners can be used, such as but not limited to buttons, elastic, snaps, buckles, and the like.

The embodiment has been shown worn on a rider's right leg, but can be worn on either the right or left leg, and can alternatively be shaped as a mirror image of the right leg configuration, to provide for matching pairs of cuffs on both the rider's right and left legs. While the invention has been described, disclosed, illustrated, and shown in various terms of certain embodiments or modifications which it has presumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the descriptions herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention. Accordingly, the present invention is not limited by the example configurations provided above. 

What is claimed is:
 1. A cuff for a bicycle rider comprising: an instep flap comprising a flexible fabric generally trapezoidal shaped, and having an instep flap top edge, an instep flap bottom edge, an instep flap front edge and an instep flap back edge; a front flap comprising a flexible fabric generally quadrilateral shaped having a front flap top edge, a front flap bottom edge, a front flap closure edge and an front flap attachment edge, the front flap attachment edge joined with the instep flap front edge; a back flap comprising a flexible fabric generally quadrilateral shaped having a back flap top edge, a back flap bottom edge, a back flap closure edge and a back flap attachment edge, the back flap attachment edge joined with the instep flap back edge; and wherein the instep flap, the back flap and the front flap are tailored to curve around a rider's ankle and a rider's shoe, so as to cover approximately from just above the top of the rider's ankle to just below the top of the rider's shoe and to follow a general contour of the rider's ankle.
 2. The cuff of claim 1, wherein the flexible fabric comprises one of: a water resistant urethane-coated nylon; a woven cloth; a non-woven cloth; and vinyl.
 3. The cuff of claim 1, wherein a portion of at least one of: the front flap; the back flap; the instep flap; and comprises reflective material.
 4. The cuff of claim 1, wherein a portion of the front flap closure edge comprises one of a hook fastener and a loop fastener and a portion of the back flap closure edge comprises a different one of the hook fastener and the loop fastener.
 5. The cuff of claim 1, further comprising reflective material attached to the back flap and the instep flap and at least partially covering a seam between the back flap attachment edge and the instep flap back edge.
 6. The cuff of claim 1, further comprising a logo attached to a portion of the front flap.
 7. The cuff of claim 1, wherein the cuff covers the rider's ankle and shoe from just above the rider's ankle to approximately one third down the front of the rider's shoe and over a back edge of the rider's shoe.
 8. The cuff of claim 1, further comprising: a top opening formed by the top edges of the front flap, the back flap and the instep flap; a bottom opening formed by the bottom edges of the front flap, the back flap and the instep flap; and wherein the top opening has a smaller circumference than the bottom opening.
 9. A protective cuff apparatus comprising: a flexible material having an outside surface and an inside surface and a first end and a second end and a top edge and a bottom edge; at least one coupler to secure the first end to the second end to shape the cuff apparatus into a cuff; the top edge having a length that is shorter than the bottom edge so that when the coupler secures the first end to the second end, the protective cuff formed by the flexible material flares outwards from the top edge to the bottom edge; and the at least one coupler operable to secure the protective cuff apparatus around an ankle and upper foot region of a person operating a bicycle, the protective cuff apparatus protecting at least a portion of a wearable item worn by the person operating the bicycle.
 10. The protective cuff of claim 9, wherein the flexible material comprises one of: a water resistant urethane-coated nylon; a woven cloth; a non-woven cloth; and vinyl.
 11. The cuff of claim 9, wherein a portion of at least one of the outside surface of the flexible material comprises reflective material.
 12. The cuff of claim 9, wherein the coupler comprises a hook fastener and a loop fastener.
 13. The cuff of claim 9, wherein the outside surface of the flexible material further comprises a logo.
 14. The cuff of claim 9, wherein the cuff covers a rider's ankle and shoe from just above the rider's ankle to approximately one third down a front portion of the rider's shoe and over a back edge of the rider's shoe.
 15. The cuff of claim 9 further comprising a top opening formed by the top edge; a bottom opening formed by the bottom edge; and wherein the top opening has a smaller circumference than the bottom opening. 